1. Field of the Invention
The present invention relates generally to communications systems and, more specifically, the present invention relates to receiving wideband communications signals.
2. Background Information
It is often necessary for devices to communicate with one another. Wireless communications systems enable signals to be transmitted between devices without the use of cables, wires or the like. Wideband or broadband signal transmissions are signals that occupy a large range of frequencies such that multiple frequencies or a range of frequencies are transmitted simultaneously thereby providing increased bandwidth in communications. Typical wireless communications often modulate wideband signals at high radio frequencies (RF) when transmitting signals between devices.
Wideband signals may suffer from significant delay spread introduced by the channel or medium through which the signal is carried between devices. In particular, a wideband signal excites the channel over a large bandwidth. Consequently, the different frequencies of a wideband signal can suffer channel distortions differently. As a result, the different frequencies in a wideband signal can arrive at the receiver with different delays and different amplitudes. The different delays and different amplitudes present in the wideband signal received by the receiver are sometimes referred to as multipath channel imperfections. When recovering data or information from the transmitted signal at the receiver, the multipath channel imperfections should be compensated to improve accuracy.
Another operation that is often performed in wideband communications is the down conversion of high frequency RF wideband signals to signals having low frequencies centered around for example direct current (DC) frequencies. In this situation, data or information is typically modulated onto a high frequency carrier at the transmitter end, transmitted through the channel and then down converted back down to a lower frequency at the receiver end. With these types of frequency conversions, it is common for a frequency offset to exist between the signal at the transmitter end and the signal at the receiver end due to mismatches between clocks at the transmitter and receiver ends. The presence of frequency offset in addition to the multipath channel imperfections described above further complicate the recovery of data or information from the signal by the receiver.